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ACTH Adrenocorticotropic hormone
CT Computed tomography
GDNF Glial cell line-derived neurotrophic factor
GDNFR Glial cell line-derived neurotrophic factor receptor
GNAS Gene encoding the alpha subunit of a stimulatory G protein
HLXB9 Homeobox protein HB9
MCT Medullary carcinoma of thyroid
MEN Multiple endocrine neoplasia
MRI Magnetic resonance imaging
PCR Polymerase chain reaction
PTH Parathyroid hormone
RET Rearranged during transfection proto-oncogene
VIP Vasoactive intestinal peptide
ZES Zollinger-Ellison syndrome

A group of heritable syndromes characterized by aberrant growth of benign or malignant tumors in a subset of endocrine tissues have been given the collective term multiple endocrine neoplasia (MEN). The tumors may be functional (ie, capable of elaborating hormonal products that result in specific clinical findings characteristic of the hormone excess state) or nonfunctional. There are three major syndromes: MEN1 is characterized by tumors involving the parathyroid glands, the endocrine pancreas, and the pituitary; MEN 2A includes medullary carcinoma of the thyroid (MCT), pheochromocytoma, and hyperparathyroidism; and MEN 2B, like MEN 2A, includes MCT and pheochromocytoma, but hyperparathyroidism is typically absent.


MEN1, also known as Wermer syndrome, is inherited as an autosomal dominant trait with an estimated prevalence of 2 to 20 per 100,000 in the general population. Approximately 10% of MEN1 mutations arise de novo. The term sporadic MEN1 has been applied to this group. MEN1 has a number of unusual clinical manifestations (Table 22–1) that occur with variable frequency among individuals within affected kindreds. Manifestations of MEN1 have been reported prior to 5 years of age; penetrance is maximal by the fifth decade of life. The diagnosis of MEN1 can be made based one of three criteria. First, it can be based on the occurrence of 2 or more primary MEN1-associated tumors (discussed later) in a single individual. Second, it can be made in a first degree relative of a clinically diagnosed MEN1 patient if they present with a single MEN1-associated tumor. Third, it can be diagnosed based on identification of a germline MEN1 mutation.

TABLE 22–1Clinical manifestations of MEN1.

Hyperparathyroidism is the most common feature of MEN1, with an estimated penetrance of 90% or greater over the lifetime of an individual harboring the MEN1 gene. The diagnosis of hyperparathyroidism is usually made through a combination of clinical and laboratory criteria similar to those used in the identification of sporadic disease (see Chapter 8). It is typically ...

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